Coded-signal relay



United States Patent CODED-SIGNAL RELAY Andrew Craig Reynolds, Jr., Waterbury, Conn., assignor to General Time Corporation, New York, N. Y., a corporation of Delaware Application July 1957, Serial No. 670,753

6 Claims. (Cl. 307140) This invention relates to remotely controlled relays and more particularly to a switch actuating relay respon sive to a coded signal.

Relays of this type are primarily intended for use in a system which includes a master signal transmitter and a plurality of relays connected to a common power supply line. Each of the relays is adjusted to respond to a particular coded signal pattern and thus the transmitter can selectively actuate any desired relay by sending the proper code on the power line. Systems of this nature have found particular utility when installed on a regular 60 cycle, A.-C. power line with the relays being responsive t0 high-frequency signals superimposed on the line by the transmitter. In this way, electrical appliances receiving power from the line can be remotely controlled from a central station.

One of the major difiiculties in setting up a system of the type referred to above is the problem of providing a simple and completely reliable coded signal relay that is immune to spurious signals, generally of a transient nature, which are found to occur in an A.-C. power system. Such transient signals are generated by various forms of electrical equipment, especially heavy equipment of the type used in factories, and have abrupt wave fronts comprising many frequency components. Often the spurious signal will include a component having the frequency at which the relays are set to respond, producing an unwanted operation which may be both inconvenient and dangerous.

It is therefore an object to provide a novel, codedsignal responsive relay which is exceptionally simple in design and completely reliable and accurate in operation. It is a collateral object to provide a relay of this type whose actuation cannot be initiated by spurious, transient signals.

In more detail it is an object to provide a relay of the type characterized above which has a novel arrangement of cam controlled switches driven by a timing motor of the type used in clocks and similar timing devices. It is another object to provide a relay responsive to coded signals which uses but a single motor and single set of cam switches with a minimum of machined parts and which is, consequently, more economical to manufacture than conventional devices intended for the same purpose. It is a related object to provide such a relay having few parts, and those operating under very light mechanical forces, so that the relay remains reliable and accurate over a long and trouble-free service life.

It is another object to provide a relay of the type referred to above that is simple and convenient to set for response to a particular desired coded signal.

In one of its aspects, it is an object of the invention to provide a novel relay having the above characteristics which can respond to a series of coded signals for the performance of a selected one of two different functions.

Other objects and advantages of the invention will become apparent on reading the attached detailed description and upon reference to the drawings in which:

Figure l is a schematic wiring diagram of a coded sig nal relay embodying the present invention.

Fig. la is a block diagram of a typical control station,

Fig. 2 is a chart detailing the sequence of switch operation in the relay shown in Fig. 1.

Fig. 3 is a fragmentary schematic wiring diagram showing a modification of the relay illustrated in Fig. 1.

Fig. 4 is a fragmentary perspective view of a time delay device utilized in the relay shown in Fig. 1.

Fig. 5 is an elevation view of the relay cams in the relay shown in Fig. 1.

While the invention will be described in connection with certain preferred embodiments, it will be understood that I do not intend to limit the invention to those embodiments. On the contrary, I intend to cover all alterations, modifications and equivalents as may be included within the sphere and scope of the invention as defined by the appended claims.

Turning first to Fig. 1, there is schematically shown a remotely controlled, switch-actuating relay 10, constructed in accordance with the present invention, connected between the A.-C. power lines 12, 13 and the device 11 which is to be remotely controlled. The A.-C. power system may include a plurality of similarly connected relays, identical to the relay 10, and a control station (Fig. 1a) having a high-frequency signal transmitter of any conventional type which is effective to superimpose a high-frequency signal on the normal 60- cycle A.-C. power system.

In order to detect high-frequency signals in the power system and cause the relay 10 to properly respond thereto, a high-frequency signal receiver 15 is connected to the power lines 12, 13. The receiver 15 is tuned to a predetermined carrier frequency and may be of any convenient type, such as are well known in systems of this nature.

In accordance with the present invention, the relay 10 includes a timing motor which is energized for a complete cycle of operation when the receiver 15 detects a signal of predetermined duration, the motor operating a novel arrangement of cam controlled switches which are effective to (a) condition a control circuit upon receipt of a second signal at a selected predetermined time following the first, and then (b) transmit a current impulse to the device 11 at the end of the cycle of motor operation by completing the conditioned circuit. In the illustrated embodiment, the relay 10 utilizes a single, self-starting, synchronous motor 20, of the type commonly employed in electric clocks and other timing devices, and the motor is energized for a single cycle of operation whenever an initiating signal is received by the high-frequency signal receiver 15. In order to energize the motor 20 in response to a high-frequency signal, the receiver 15 actuates a control relay 21 through a circuit including the contacts 16 which closes a set of contacts 22 and completes a circuit, through the normally closed contacts 23, connecting the motor 20 to the A.-C- power lines 12, 13. The motor 20 is provided with a gear box 25 which rotates a camshaft 26 through a time delay device 30, to which later detailed reference will be made. In the preferred embodiment, the motor 20 and the gear box 25 are effective to rotate the cam shaft 26 at an angular speed of 1 R. P. M.

Since the initiating signal which causes the energizetion of the control relay 21 and the closing of the contacts 22 lasts only a short time interval, a circuit is provided to seal-in the motor 20 through a complete cycle of operation. This is accomplished by providing a cam 31 fixed to the camshaft 26 which is effective, following the initial energization of the motor 20 and the first rotational movement of the camshaft 26, to close the contacts 32 and complete a circuit by-passing the contacts 22, 23 to maintain the motor 20 energized until the cam 31 again opens the contacts 32. 'In the embodiment illustrated, the cam 31 is provided with a single drop off portion 33 allowing the contacts 32 to open, and, therefore, once the contacts 32 are closed by the cam 31, they remain closed for a full revolution of the camshaft 26. Since the shaft 26 rotates at l R. P. .M., the cycle of operation for the relay 10 requires a time in terval of one minute.

It will be appreciated that when a number of relays similar to the relay 10 are connected to a common A.-C. power system, each will respond in the manner described above when the master transmitter imposes an initiating signal onto the common A.-C, power system. In order to select the relay 10 for operation, to the exclusion of the other, differently coded, relays, a second high-frequency signal must be imposed on the lines 12, 13 following the first signal by a particular, predetermined time interval. In the present embodiment, when a second, properly timed, signal is received by the signal receiver 15, the control relay 21 is energized and sealedin to condition a control circuit connected to the device 11.

So that the control relay 21 will be energized and sealed-in only by a signal occurring at a selected predetermined time during the operating cycle of the relay 10, a code selector cam 35 is fixed to the camshaft 26. The cam 35 is provided with a lobe 36 which maintains the contacts 16 closed when the camshaft 26 is in its normal rest position (Fig. so that the receiver 15, responding to the initiating signal, may energize the control relay 21 through the closed contacts 16. However, as soon as the camshaft 26 begins rotation and the motor 20 is sealed-in for a complete cycle of operation, the lobe 36 ceases to close the contacts 16 and the circuit between the receiver 15 and the control relay 21 is broken. The contacts 16 are reclosed only within a selected time interval during the cycle of operation of relay by providing the cam 35 with an angularly adjustable lobe 37. At a selected time during the operating cycle of the relay 10, the adjustable lobe 37 will be effective to close the contacts 16. Therefore, by transmitting a high-frequency signal on the common A.-C. power system during precisely that time interval, the receiver will be effective to energize the control relay 21 through the then closed contacts 16. In the illustrated embodiment, the adjustable lobe 37 is positioned directly opposite the fixed lobe 36 (see Fig. 5), and therefore the proper coded signal for causing the relay 10 to transmit a current impulse to the control device 11 comprises an initial signal impulse followed in thirty seconds by a second signal impulse.

In order to seal-in the control relay 21 when it is energized by the second signal impulse of the code and thus condition the control circuit for the device 11, a cam 41 is fixed to the camshaft 26. The cam 41 is effective to close the normally open contacts 42 following the revolution of the camshaft 26 through a short angular distance. Closing the contacts 42 concurrently with the momentary closing of the contact 22, caused by the actuation of the control relay 21 when the second signal of the code is received, will complete a circuit activating the control relay 21 which by-passes the con tact 16 so that the relay will seal itself in. It will be appreciated that the contacts 42 are open when the control relay 21 is first activated by the initiating impulse of the coded signal, and, therefore, the control relay will not be sealed in when the contacts 22 close to initially energize the motor and being the operating cycle of the relay 10.

In order to complete the conditioned control circuit when the control relay 21 is sealed-in and thus transmit a current impulse to the device 11, an operating cam 45 is fixed to the camshaft 26 and is provided with a drop off portion 46 which is effective to close the normally open contacts 47. Closing of the contacts 47 will, if the control relay 21 has been sealed-in by the proper coded signal, cause completion of a control circuit through the contacts 47, 42 and 22 which will con nect the device 11 directly to the lines 12, 13 of the A.-C. power system. The duration of the current impulse supplied to the device 11 will depend upon the dimension of the drop off portion 46 on the cam 45, and in practice it has been found desirable to standardize this current impulse interval to either 3, 5 or 8 seconds by providing standard cams with suitable elongated drop off portions.

It will be apparent that the device 11 may consist of a visual or audible signal, such as an electric light or bell respectively, or may comprise a latching relay which will be tripped by the current impulse supplied through the relay 10 so as to switch on, or off, an electrical appliance of any desired type.

It will be understood that the angular position of the adjustable lobe 37 on the code selector cam 35 will determine the particular coded signal to which the relay 10 will respond. In order to set the relay 10 for response to any given coded signal, therefore, it is suflicient merely to change the angular relationship of the lobe 37 on the cam 35. To facilitate this adjustment, the lobe 37 is formed integrally with an arm 51 that is mounted loosely on the camshaft 26. A nut 52 is threaded onto the end of the camshaft 26 so that the nut may be drawn up for tightening the arm 51 against the cam 35 and thus rigidly fix the adjustable lobe 37 in any desired angular position. Suitable indicia 53 may be inscribed on the face of the cam 35 so that the lobe 37 may be conveniently and correctly positioned (see Fig. 5).

For the purpose of initiating the operative cycle of the relay 10 only when a high-frequency signal of sufiicient predetermined duration is received, and thus prevent operation of the relay by spurious, transient signals, the time delay device 39 is provided. As mentioned above, spurious high-frequency signals are often induced in an A.-C. power system by various electrical devices, these signals being a form of static and possessing frequency components within a range which will cause a response from the high-frequency signal receiver 15. Such spurious signals, however, are of short duration, and therefore a transient signal received by the high-frequency signal reciver 15 will cause only a momentary activation of the control relay 21, which only briefly closes the contacts 22. By providing the motor 26 with a time delay device, the brief closings of the contacts 22 caused by spurious, transient signals will be of insurTicient duration to seal-in the motor 26 and thus will not initiate a false relay operating cycle.

In the present embodiment, the time delay device 30 comprises a spring-biased, lost motion, driving connection between the output shaft of the motor 29 and the camshaft 26, which is arranged so that when the motor starts rotating, it must first overcome the spring force and take up the lost motion before the camshaft 26 is rotated. To provide the lost motion connection, the gear box 25 associated with the motor 20 is connected to drive a disk 60 mounted concentrically with, but independently of, the cam shaft 26. The disk 60 rotates the camshaft 26 by means of a pin 61 extending axially of the camshaft through a hole 62 of somewhat greater diameter formed in the cam 31. It can be seen that when the pin is disposed at one edge of the hole 62 (see Fig. 5), the motor 20 must rotate the disk 60 through a distance approximately equal to the diameter of the hole 62 so that the pin 61 may engage the opposite side of the hole and impart a rotational force to the cam 31.

To insure that the disk 60 and the motor 20 are properly backed off so that the pin 61 is adjacent the proper edge of the hole 62, a torsion spring 63 is fixed to the cam shaft 26 and is tensioned to exert a resilient force against the pin 61 in a direction opposite to that imparted by the motor 20. It can thus be seen that momentary energization of the motor 20, caused by briefly closing the contacts 22 as a result of spurious, transient signals being picked up by the high-frequency signal receiver 15, will only cause the disk 68 to begin revolving and start tocarry the pin 61across the hole 62. Upon the almost immediate deenergization of the motor 20, the torsion spring 63 will return the pin 61, disk 60, and the gear trainincluded within the gear box 25, back to their original starting positions. It will be apparent then that the operating cycle of the relay 16) can be initiated only by energizing the motor 20 for a sustained, predetermined period, which will be the case when a true signal impulse of several seconds duration is transmitted onthe common A.-C. power system. A practical duration period for an initiating signal has been found to be four seconds.

To hold the camshaft 26 and the cam 31 in their starting positions against the reactive force exerted by the torsion spring 63, the inherent detenting effect exerted by the switch actuator for the contacts 32 is utilized. As can be seen in Figs. 4 and 5, the contacts 32 are provided with a resilient switch actuator 55 having a detent portion 56 which drops into the notch-like drop off portion 33- of the cam 31. It will be understood that the engagement of the switch actuator 55 Within the drop off portion 33 will hold the cam 31 and the camshaft 26 in their respective starting positions with a detent action. When the motor 20 remains energized for a time suflicient to bring the pin 61 into engagement with the opposite side of the hole 62, the cam 31 will be rotated so as to bring the detent portion 56 of the switch actuator 55 out of the drop off portion 33 so'that the contacts 32 are closed and the operating cycle of the relay initiated.

In order to minimize the resilient force required to be exerted by the torsion spring 63, while insuring that the force is suffiicient to back off the disk 61 and the gear train in'the gear box 25, the motor 20 preferably includes an automatically operating clutch of the type which is commonly employed for such purposes. In clutch motors of this type, the motor armature is automatically engaged with a power output driving train upon energization of the motor winding, and is disengaged upon the deenergization of the motor winding. An example of a motor of this type having such an automatically operating clutch construction can be seen by reference to the United States Patent to Schellens, No. 2,334,040 issued November 9, 1943. It will be sufficient for present purposes to observe that'the armature in the motor 20 is connected to the driving train in the gear box 25 only when the motor is energized. When the motor is only briefly energized, through the action of a spurious signal causing the contacts 22 to flutter momentarily, the gear train in the gear box 25 and the disk 60 are briefly advanced by the motor armature and then completely disconnected from the armature. 1 Thus, the torsion spring 63 need rotate only the disk' 60 and the gears within the gear box 25 back to their initial starting positions,and is not required to rotate the entire armature of the motor 20.

Also in accordance with the invention, a second control relay may be operated by the high-frequency signal receiver and connected so as to selectively direct the current impulse, created by closing the contacts 47, to either one of two control devices in response to the presence or absence of a third signal impulse in the coded signal received by the relay 10. This modification of the invention is illustrated in Fig. 3, in which the outlined block portion A is substituted for the outlined block portion B in the embodiment shown in Fig. 1, and the terminals 71 and 72 are connected to the terminals 71a, 72a, respectively, which also appear in the Fig. 1 modification.

In the Fig. 3 embodiment, the relay 10 is connected current impulse is to be directed.

to two separate devices to be controlled, 73, 74, and a second control relay 75 is connected to the high-frequency signal receiver 15 through the contacts 71, 72 and 71a, 72a. The control relay 75 operates normally closed contacts 76in circuit with the device 74, and normally open contacts 77 in circuit with the device 73. Thus, if a third signal impulse in a coded signal sequence is detected by the signal receiver 15 at the end of the relay operating cycle when the contacts 47 are closed, that third signal will-activate the relay 75 to close the contacts 77 and direct the-current impulse through the contacts 47 to the device 73. However, if there is no third signal in the coded signal sequence, the closing of the contacts 47 at the end of the operating cycle of the relay 10 will direct thecurrent impulse through the normally closed contacts 76 to the device 74.

- Thus, the presence or absence of a third signal impulse in the coded signal, timed to occur at the end of the operating cycle of the relay 10, will determine to which of the 'two controlled devices 73 and 74 the controlling In a practical case, it has been found that the third signal of a three impulse coded signal must be of approximately ten secs onds duration so that the contacts 77 are closed when the cam 45 closes the contacts 47 and completes the control circuit. It will be understood that the reception of a ten-second high-frequency signal by the receiver 15 will, have no effect on the first control relay 21 since the connection between the receiver 15 and the control relay 21 will be broken by the contacts 16 being then open.

Rsum of operation Briefly summarizing the operation of the relay 10, and with particular reference to the chart in Fig. 2, it will be recalled that the relay 10 can be adjusted to respond to a particular coded signal by angularly positioning the adjustable lobe 37 on the code selector cam 35. In the illustrated embodiment, the adjustable lobe 37 has been positioned directly opposite the fixed lobe so that there is a half revolution, or 30 second interval, between closing of the contacts 16 by the lobe 36 and closing the contacts by the lobe 37.

' When the relay 10 is at rest, the contacts 16 and 23 are closed, and therefore an initiating signal impulse, received by the signal receiver 15, will activate the control relay 21 and close the contacts 22 to energize the motor 20. Following the few seconds time delay imposed by the device 30, the motor 20 begins to rotate the camshaft 26. This immediately closes the contacts 32 to seal-in the motor for a complete operating cycle, and opens the contacts 16 so that subsequent signals received by the signal receiver 15, which may represent other codes, cannot actuate the control relay 21.

Early in the operating cycle, the contacts 42 are also closed so that any subsequent actuation of the control relay 21 will seal-in that relay and condition the control circuit. Thirty seconds following the initial rotation of the camshaft 26, the adjustable lobe 37 on the code selector cam 35 is effective to again close the contacts 16, so that a second impulse of the coded signal concurrently received bythe signal receiver 15 will be effective to condition the control relay 21, which will seal itself in by means of the circuit through the contacts 22 and 42.

When the control relay 21 is sealed-in, the control circuit is conditioned and at the end of the cycle, when the cam 45 closes the contacts 47, a current impulse will be transmitted to the control device 11 by the control circuit through the contacts 22, 42 and 47. The length of the control current impulse is determined by the length of the drop ofi portion 46 on cam 45 and when the contacts 47 open, the control current impulse is interrupted. Almost immediately thereafter, the cam 31 will open the contacts 32, deenergizing the motor 20, and ending the operating cycle of the relay 10. At the same time, the

cam 35 closes the contacts 16 and the cam 41 closes the contacts 23 so that the various circuits are again in their initial starting positions ready to respond to subsequent high-frequency signals having the proper code.

It will be readily seen that the relay 10 is of an exceptionally simple design in that it relies upon cam control switches which can be simply and economically manufactured, and utilizes a timing motor of the type conventionally used in electric clocks and similar devices. Such motors operate in synchronism with the 60 cycle frequency of the ordinary A.-C. power system and, therefore, impose quite a rigid accuracy on the opening and closing of the several contacts making up the relay.

It will also be appreciated that since only ordinary switch and motor construction is utilized in the novel arrangement comprising the relay, the few parts operate under quite light mechanical forces so that the relay will remain completely reliable and accurate over long periods of service use. It will also be apparent that the relay 10 can be quite compactly constructed so as to permit convenient and simple installation. A significant factor in contributing to the compactness of the relay design is the fact that only a single cam shaft is utilized and thus only a single motor and driving connection is required.

I claim as my invention:

1. A coded-signal relay for transmitting a current impulse to a controlled device comprising, in combination, a signal receiver, a constant speed timing motor, means including said receiver for energizing said motor through a complete cycle of operation in response to a signal of predetermined duration, means concurrently controlled by said receiver and said motor to condition a control circuit upon receipt of a second signal at a predetermined selected time during said cycle, output terminals in said control circuit, and means controlled by said motor and efiective at the end of said cycle to complete said control circuit and thus transmit the current impulse to said output terminals for operation of said controlled device.

2. A coded-signal relay for transmitting a current impulse to a controlled device comprising, in combination, a signal receiver, a constant speed timing motor, means including said receiver for energizing said motor in response to a signal of predetermined duration, means including a cam controlled switch for maintaining energization of said motor through a complete cycle of operation, means including switches concurrently controlled by said receiver and said motor to condition and seal-in a control circuit upon receipt of a second signal at a predetermined time during said cycle, output terminals in said control circuit, and means including a cam controlled switch etiective at the end of said cycle to complete said control circuit and thus transmit the current impulse to said output terminals for operation of said controlled device.

3. A coded-signal relay for transmitting a current impulse to a controlled device comprising, in combination, a signal receiver including a relay which is actuated when a signal is received, a constant speed timing motor, means for energizing said motor when said relay is actuated, means for maintaining energization of said motor through a predetermined cycle, means controlled by said motor for actuating and scaling in said relay when a second signal is received at a selected time following the start of said cycle, output terminals, and means, controlled by said motor and effective only when said relay is actuated, for transmitting a current impulse to said output terminals at the end of said cycle for operation ofsaid controlled device.

4. A coded-signal relay for transmitting a current impulse to a controlled device comprising, in combination, a signal receiver including a relay which is actuated when a signal is received, a constant speed timing motor, means for energizing said motor when said relay is actuated, means including a cam controlled switch for maintaining energization of said motor through a predetermined cycle, means including a cam controlled switch operated by said motor for sealing in said relay only when a second signal is received to actuate the relay at a selected time following the start of said cycle, output terminals, and means, including a cam controlled switch operated by said motor, etfective for transmitting a current impulse to said output terminals at the end of said cycle only when said relay is closed for operation of said controlled device.

5. A coded-signal relay for transmitting a current impulse to a controlled device comprising, in combination, a signal receiver including a relay which is energized when a signal is received, a constant speed timing motor, means for energizing said motor when said relay is energized, means for maintaining energization of said motor through a predetermined cycle only when said relay remains energized for a minimum initial time interval, means operated by said motor efiective at a selected time during said cycle for sealing in said relay when a second signal is concurrently received to energize the relay, output terminals, and means operated by said motor for transmitting, when said relay is energized, a current impulse to said output terminals at the end of said cycle for operation of said controlled device.

6. A coded-signal relay for selectively transmitting a current impulse to one of two controlled devices comprising, in combination, a signal receiver including a relay which is energized when a signal is received, a constant speed timing motor, means for energizing said motor when said relay is energized, means for maintaining energization of said motor through a predetermined cycle, means operated by said motor elfective, at a selected time during said cycle, for scaling in said relay upon receipt of a second signal to energize the relay, an output circuit having two alternate sets of output terminals, means operated by said motor for transmitting a current impulse to said output circuit at the end of said cycle when said relay is energized, and means, including a second relay energized by said receiver, for directing said current impulse to one set of output terminals when the second relay is energized as a result of a third signal for operation of one of said controlled devices, and to the other set of output terminals when the second relay is not so energized for operation of the other of said controlled devices.

No references cited. 

